RU2707301C1 - Low-molecular mimetic bdnf as an agent for treating opioid dependence - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: invention refers to medicine and concerns the use of bis-(N-monosuccinyl-L-seryl-L-lysine) hexamethylene diamide as an agent for treating opioid dependence.EFFECT: invention provides treating opioid dependence.1 cl, 2 dwg, 1 tbl, 2 ex

Description

The invention relates to the pharmaceutical industry and relates to a new use of the known bis- (N-monosuccinyl-L-seryl-L-lysine) hexamethylene diamide as an agent for the treatment of opioid dependence.

According to official UN statistics, over the past 10 years there has been a sharp increase in the number of Russian citizens suffering from drug addiction. Every year, 90 thousand citizens of Russia begin to use drugs, despite the fact that today medical institutions in the country can accept no more than 50 thousand drug addicts per year for inpatient treatment. Thus, in the current situation, the development of innovative drugs for the pharmacotherapy of addiction diseases continues to be relevant.

Substance abuse (PAS) is often combined with mood disorders and depressive disorders (Butelman ER et al., Am J Addict. 2017 Sep; 26 (6): 632-639.). Depression preceding the onset of drug-related disorders reduces the chances of stable remission in cocaine and heroin addiction. In general, depressive disorders that occur before the onset of addiction to surfactants reduce the chances of remission of patients with a narcological profile, similar to depressions induced by alcohol and opioid drugs (Samet S. et al., Addiction. 2013 Jan; 108 (1): 115 -23). Chronic use (over 90 days) of opioid analgesics significantly increases the risk of developing new bouts of depression, which entails the inclusion of antidepressants in the pharmacotherapy course (Scherrer JF et al., J Affect Disord. 2017 Mar 1; 210: 125-129).

According to experimental studies, a selective serotonin reuptake inhibitor fluoxetine (10 mg / kg, ip, twice a day for 9 days) stopped the manifestation of certain symptoms of morphine withdrawal syndrome in mice (Singh VP et al., Methods Find Exp Clin Pharmacol. 2003 May; 25 (4): 273-80). Venlafaxine, a non-selective serotonin and norepinephrine reuptake inhibitor, impaired tolerance and morphine dependence by modulating the L-arginine / NO / cGMP signaling cascade (Mansouri MT et al., Endocr Metab Immune Disord Drug Targets. 2018; 18 (4): 362-370). On the other hand, when evaluating the effect of the serotonin reuptake inhibitor sertraline on the brain reward system using the conditioned seat preference method in rats, it was shown that per se in effective doses, sertraline showed reinforcing properties, and at a dose of 5 mg / kg it enhanced the reinforcing effects of morphine, increasing residence time in a chamber associated with the action of morphine (Ciubotariu D, Nechifor M., Rev Med Chir Soc Med Nat Iasi. 2014 Jul-Sep; 118 (3): 712-6). Paroxetine (15 mg / kg) and fluoxetine (5 and 10 mg / kg) antidepressants showed a similar positive motivational effect in the “conditional location preference” test, similar to the action of opioid analgesics and other surfactants, while the dose was 10 mg tricyclic antidepressant amitriptyline / kg, on the contrary, caused an aversive reaction in animals, or "avoidance" of the place associated with the action of the drug (Subhan F et al., Eur J Pharmacol. 2000 Nov 24; 408 (3): 257-63).

In studies of Assadi A. et al. (2011) when analyzing the effect of synthetic antidepressants on rat morphine-induced site preference, it was found that all drugs, when administered intraperitoneally and intracerebroventricularly, enhanced the secondary reinforcing effects of morphine (Assadi A. et al., Iran J Pharm Res. 2011 Summer; 10 (3 ): 916-26). Morphine acts on the reward system by activating mu receptors that facilitate dopaminergic transmission, and serotonin is also a powerful stimulant of dopamine release. Thus, it can be assumed that an increase in the morphine-induced preference for the site with drugs for the treatment of depressive disorders can be associated with an increase in the concentration of dopamine and serotonin in the synaptic cleft, which is determined by the mechanism of action of modern synthetic antidepressants.

According to Zilkha N. et al. (2014), performed in rats, heroin, when given briefly, promotes the formation of depressive-like symptoms, causing changes in the BDNF content in a number of brain regions similar to those observed in modeling depression in animals (Zilkha N. et al., J Neurochem. 2014; 130 (4): 575-82).

Brain-derived neurotrophic factor (BDNF) is considered as a positive modulator of various forms of neuronal plasticity. In the context of addictive behavior, the role of BDNF is best characterized for the chemical dependence caused by cocaine or other psychostimulants through their effect on the mesolimbic dopaminergic system (Hall FS. Et al., Neuropsychopharmacology. 2003; 28: 1485; Graham DL, et al. Nat Neurosci . 2007; 10: 1029). Opiates also act on the ventral tegmental region-adjacent nucleus (VTA-NAc) to induce “reinforcement”, stimulating the “reward” region during acute administration and causing the formation of dependence in chronic use.

Studying the role of BDNF in the pathological circle, the ventral region of the tire-adjacent nucleus (VTA-n.accumbens) is an area of increased interest and heated debate in assessing the mechanism of formation of rewards and memory for opiates. A recent study by Koo and colleagues (2012) shows that BDNF in VTA counteracts the reinforcing effects of morphine by decreasing activity in DAergic neurons projected into the nucleus accumbens (Koo JW. Et al., Science. 2012; 338 (6103 ): 124-8). When studying the role of the BDNF-TrkB signaling pathway in VTA-NAc in the action of morphine by evaluating the secondary reinforcing properties in the test “conditionally reflex site preference” (URPM), it was shown that knockdown mice using the bdnf gene increase the reinforcing effect of morphine in doses of 5.0 and 15 mg / kg. Similar effects were noted for knockdown mice by the TrkB receptor gene in VTA (Koo JW, et al., Science. 2012; 338 (6103): 124-8). Apparently, local BDNF signaling in VTA DA neurons may be responsible for regulating the mechanisms of "reward" to morphine. These data are at variance with earlier work by Vargas-Perez et al. (2009), which showed that BDNF in VTA neither counteracts nor facilitates morphine-based “reward”, but only “switches” opiate reinforcement from dopamine-independent to dopamine-dependent (Vargas-Perez H, et al., Science . 2009; 324: 1732). This occurs through BDNF-dependent reversal of GABA currents in VTA neurons from inhibitory to excitatory, and it is believed that this effect underlies the negative aversive state associated with opiate withdrawal syndrome (Vargas-Perez N. et al., J Neurosci. 2014; 34 (23): 7899-909).

In chronic exposure, opiates induce a series of biochemical and morphological changes in VTA. If the effect of opiates on the expression of BDNF in VTA is controversial (Vargas-Perez H, et al., Science. 2009; 324: 1732), then it is considered proven to decrease the regulation of intracellular signaling cascades associated with BDNF and reduce the size of the bodies of dopaminergic neurons in VTA under the action opiates (Berhow MT, et al. Neuroscience. 1995; 68: 969; Mazei-Robison MS, et al. Neuron. 2011; 72: 977), which is not observed when using psychostimulants. Some of these biochemical and morphological changes in VTA are eliminated immediately after the introduction of BDNF into the indicated region of the brain (Berhow MT, et al. Neuroscience. 1995; 68: 969).

The presented data indicate that, unlike cocaine and psychostimulants, opiates and BDNF can have a counteracting effect on dopaminergic neurons of VTA, which suggests the antagonistic role of endogenous BDNF-TrkB signaling in modulating adaptive responses of the VTA-NAc pathway to chronic action opiates.

The scientific literature regarding BDNF-ergic signaling in the ventral tegmental region with abuse of opiates is not always consistent. In some studies, BDNF protein in VTA was significantly reduced within 1-14 days after cessation of chronic exposure with morphine (Chu NN. Et al., Brain research. 2007; 1182: 90-98), in other studies, an increase in BDNF content through 7 days after cessation of morphine administration (Mashayekhi FJ. Et al., Neurochem Res. 2012; 37: 1517-1523). Another study showed that the expression of BDNF mRNA in VTA did not change after chronic use of morphine, either immediately after administration or after spontaneous withdrawal after 24 hours (Numan S. et al., J Comp Neurol. 1999; 403: 295-308). Prolonged morphine-induced changes in BDNF in VTA are presumably mediated by trimethylation of histone H3K9, i.e., an epigenetic modification that is associated with the suppression of transcription on the promoter II of the bdnf gene (Mashayekhi FJ. Et al., Neurochem Res. 2012; 37: 1517-1523). It is believed that the extinction of aversive memory when morphine is canceled requires the epigenetic regulation of transcription of the bdnf gene in the ventromedial prefrontal cortex by activation of the ERK-CREB signaling pathway (Wang WS. Et al., J Neurosci. 2012; 32 (40): 13763-75).

Earlier in the V.V. Research Institute of Pharmacology Zakusova created a low molecular weight dipetide mimetic of the 4th loop of BDNF hexamethylene diamide bis- (N-monosuccinyl-L-seryl-L-lysine), or GSB-106 (Fig. 1), which has a pronounced antidepressant effect in in vivo experiments (T. Gudasheva . et al., Bioorgan. chemistry. 2012; 38 (3): 280-290), (Gudasheva TA, et al., Dokl Biochem Biophys. 2015; 460: 20-2; Povarnina PY, et al., Acta Naturae . 2018; 10 (3): 81-84). Western blot analysis showed the ability of a low molecular weight BDNF mimetic GSB-106 compound to selectively activate TrkB receptors and its intracellular AKT / MAP kinase signaling pathways on a culture of hippocampal cells (Gudasheva T.A. et al., Reports of the Academy of Sciences. 2013; 451 (5) : 577-580).

However, data on the nature of the possible anti-addictive potential of a new psychotropic drug with an original mechanism of action are currently not available.

Animals. This study was performed on outbred white male rats (Federal State Budgetary Scientific Institution Scientific Center for Biomedical Technologies of the Federal Medical and Biological Agency, Stolbovaya Branch). Animals were kept in 6 individuals per cage under vivarium conditions of the Federal State Budget Scientific Educational Institution “V.V. Zakusova ”(temperature 21-23 ° C, relative humidity 40-60%) with natural light and free access to water and briquetted feed for 10 days before the start of testing. The organization and conduct of work was carried out in accordance with the order of the Ministry of Health of Russia No. 199 of April 1, 2016 “On approval of the rules of good laboratory practice”. The animals were kept in accordance with SP 2.2.1.3218-14 "Sanitary and epidemiological requirements for the design, equipment and maintenance of experimental biological clinics (vivariums)" dated August 29, 2014 No. 51. The experiments were approved by the Commission on Biomedical Ethics of the Federal State Budget Scientific Institution “V.V. Zakusov ".

Preparations. Morphine hydrochloride (Minmedbioprom association Chimkentbiofarm, substance) was dissolved in water for injection and was administered intraperitoneally (ip) at a dose of 5 mg / kg based on 0.1 ml / 100 g of rat mass. Animals of the control group received water for injection. GSB-106 (hexamethylene diamide bis- (N-monosuccinyl-L-seryl-L-lysine)) in the form of a substance synthesized at the V.V. Zakusova ”, in an effective dose of 0.1 mg / kg, was dissolved in water for injection and injected ip at the rate of 0.1 ml / 100 g of rat mass.

Methodologies

Test "conditioned reflex preference of the place" (URPM) to assess the secondary supporting properties of psychoactive substances.

The apparatus for assessing the behavior of “place preference” in rats (SD Instruments, San Diego, CA, USA) is a camera consisting of 3 compartments: left (27 × 22 × 30 cm), right (27 × 22 × 30 cm ) and central (14 × 22 × 30 cm), having floors of different structures (left - smooth, right - grooved, central - trellised) and differently painted walls (left compartment with vertically drawn black lines on a white background, right compartment - with horizontal black lines on a white background). The camera compartments can be isolated from each other using guillotine-like dampers. The installation is equipped with a PAS motion indication system and its corresponding PAS764 SDI program coupled to a computer, which allows recording animal behavior indicators online and presenting it in a form adapted to standard Windows programs.

The URPM test refers to one of the generally accepted and validated approaches for assessing the ability of substances that affect the central nervous system to cause the formation of drug dependence in laboratory animals. The results of the use of the URPM test ("conditioning place preference") are in good agreement with clinical data demonstrating the activity of psychotropic substances in humans when they are taken for medical reasons or with unjustified illegal use. The reaction of “place preference supported by a pharmacological agent” was used earlier in studying the effects of morphine, methamphetamine, cocaine, etc.

To assess the effect of the studied drug candidate on the secondary reinforcing effects of morphine, the previously described technique with modifications was used (Fan Y. et al., Neurosci Bull. 2012; 28 (5): 567-76; Budygin EA et al. PNAS, 2004; 101 ( 20): 7781-7786; Buffalari DM et al. Pharmacol Biochem Behav. 2014; 124: 320-5).

The testing procedure includes five phases:

1st phase (1st day of the experiment) - adaptation and reduction of the severity of the orientational reaction during the subsequent experiment, for which each rat is placed in the central compartment of the chamber for 15 minutes with open shutters between the compartments; rats move freely between the compartments of the chamber;

Phase 2 (day 2 of the experiment) - preliminary testing of animals (pre-test) in the URPM apparatus for 15 minutes without the introduction of substances with automatic registration of rat movement between 3 chamber compartments and recording the number of visits to each chamber compartment and the time spent by animals in each of the compartments; data is processed and animals that were in one of the camera compartments (left or right) ≤25% of the time according to the ratio t _sec = lion / right × 100% are excluded from the experiment. The animals remaining after selection are randomly divided into groups and included in the experiment. During preliminary testing, animals may be excluded from the experiments as not satisfying the selection criterion for the time spent in the left or right compartments of the chamber, in addition, animals with low weight and noticeable violations of general behavior are not included in the study.

Phase 3 (3-12 days of the experiment) - training (or “conditioning”), in which the introduction of the test substance (or solvent) is combined with the placement of animals in a specific compartment of the chamber. When training, the drug candidate, morphine and solvent (control) are administered to rats parenterally and animals are placed in a specific compartment of the chamber (always the same for a given substance) for 30 minutes with the shutter down, separating this compartment from the central one. Injections of the test substance and solvent alternate. Thus, 5 combinations are performed with the introduction of the test substance and morphine with the animal landing in the left compartment of the chamber every other day. Rats of the control group receive daily solvent injections before landing in the opposite compartment of the experimental compartment of the chamber.

4th phase (13th day of the experiment) - testing of animals for the presence of “preference for a place” behavior 24 hours after the end of the training phase (“test 1”). No substances are administered on this day, the time spent by animals in the left and right compartments of the chamber is recorded for 15 minutes with the flaps raised between the compartments, which allows the animals to move freely inside the chamber.

The 5th phase (the 21st day of the experiment) - testing animals for the presence of behavior "preference for places" 7 days after the last injection of the studied drugs ("test 2"). On this day, the time spent by animals in the left and right compartments of the chamber is recorded for 15 minutes with the flaps between the compartments raised, which allows the animals to move freely inside the chamber.

The reinforcing properties of the test compound are evaluated by the difference in the time (Δ _sec ) of the rats' stay in a certain, for example, left (associated with the test substance) and right (associated with the control solution) chamber compartments. Positive values correspond to a place preference reaction; negative values correspond to an aversive reaction.

Formation of opiate dependence and assessment of somatic manifestations of morphine withdrawal syndrome.

In rats, morphine dependence was developed and behavior was assessed for the presence of specific signs of withdrawal syndrome (CO) in accordance with the standard scheme described earlier (Konstantinopolsky MA et al., Expert wedge, pharmacol. 1992. 55 (1): 21 -24). To obtain morphine-dependent animals, the drug was administered to animals in increasing doses of 10-20 mg / kg, 2 times a day after 8 hours for 4 days: on the 1st day, 10 and 10 mg / kg on the 2nd day - 10 and 20 mg / kg, on the 3rd day - 20 and 20 mg / kg, on the 4th day - 20 and 20 mg / kg; 5th day - 20 mg / kg in the morning. Hexamethylene diamide bis (N-monosuccinyl-seryl-L-lysine) at a dose of 0.1 mg / kg, ip, was administered once 30 minutes before morphine on the 5th day of the experiment. Testing of animals for the presence of specific signs of morphine withdrawal syndrome (CO) was performed on the 5th day of the experiment for 5 min in an “open field” (illuminated round arena with a diameter of 80 cm) 15 min after administration of an opiate receptor antagonist naloxone (“Du Pont De Nemours Int. SA, Swiss ") at a dose of 1.0 mg / kg to provoke CO. Control animals were injected with water for injection once daily in the morning for 5 days, and on the 5th day of the experiment before testing, naloxone at a dose of 1.0 mg / kg was administered. Behavioral reactions of animals (motor activity (DA), stance, grooming, bowel movements) and specific signs of morphine CO (16 indicators) were recorded for all groups. Discrete signs of abstinence (diarrhea - in points, brushing and gnashing of teeth - according to the number of acts) were evaluated quantitatively and alternatively, the rest - in an alternative form on the principle of "yes" - "no". The total index (SI) of the severity of CO for each animal and the average values for the experimental and control groups were calculated on the basis of alternative signs with the maximum possible value of SI equal to 16 points. The average value of the severity of CO in the morphine group (active control) was taken as 100%.

When studying the effect of the dimer dipeptide mimetic of the 4th loop of BDNF bis- (N-monosuccinyl-L-seryl-L-lysine) hexamethylene diamide, which has antidepressant properties, on the manifestation of morphine withdrawal syndrome in animals with a drug-dependent dependence, it was first shown that bis- (N-monosuccinyl-L-seryl-L-lysine) at a dose of 0.1 mg / kg reduced the severity of behavioral signs of withdrawal syndrome by 55.2% with a single dose and by 45.6% with subchronic administration compared to the active control group, in particular eliminating or significantly weakening such signs of physical dependence as gnashing of teeth, piloerection, rhinorrhea, shaking of the legs and head, attempts to escape.

Statistical processing of the obtained results was performed using one-way analysis of variance (ANOVA), Mann-Whitney test for independent groups and Wilcoxon test for dependent groups. The normality of the data distribution was checked using the Shapiro-Wilks test. The critical significance level is α = 0.05. Data are presented as mean values.

The invention is illustrated by the following examples.

Example 1. The effect of hexamethylene diamide bis- (N-monosuccinyl-L-seryl-L-lysine) on the formation of the supporting effects of morphine

The experiments were performed on outbred male rats (n = 80) with a body weight of 220-250 g.

Animals selected during the background ("pre-test") testing were randomly divided into the following groups:

group 1 "Control": water for injection + water for injection (5 injections);

group 2 "GSB-106": water for injection + GSB-106 (5 injections);

group 3 "Morphine" ": water for injection (5 injections) + morphine (5 injections);

group 4: “GSB-106 + morphine”: GSB-106 (5 injections) + morphine (5 injections).

An opiate agonist of morphine hydrochloride at a dose of 5.0 mg / kg, ip, which shows pronounced reinforcing properties in the URPM test, was used as a drug with a pronounced narcogenic potential. The choice of dose is based on literature data and previously obtained own experimental data (Gong YX. Et al., Acta Pharmacol Sin. 2007; 28 (1): 10-8). The number of animals in each group is 11-12.

During preliminary testing of rats, rats that did not differ in the preference of this or that compartment and corresponded to the selection criterion of more than 25% were selected in the apparatus for evaluating the reaction of URPM (Fig. 1 "pre-test"). After the administration of morphine at a dose of 5.0 mg / kg / day for 5 days (a total of 5 ip injections), a pronounced stable formation of a preference for the right compartment of the chamber associated with the action of an opiate receptor agonist was noted, which significantly exceeds the control group (p < 0.01). Morphine statistically significantly increased the residence time of animals in the right compartment (p <0.001) during the first and second tests compared to the preliminary testing data (“pre-test”), that is, the effect of preference for the place associated with the action of morphine remained for 7 days after the last injection of an opioid analgesic. At the same time, the time spent by animals in the left compartment of the chamber was reduced compared with the “control” and pre-test groups, which indicates the validity of this technique for evaluating the secondary reinforcing properties of psychoactive substances.

Compound GSB-106 with subchronic administration at a dose of 0.1 mg / kg did not affect the length of stay in the chamber associated with the action of the studied compound (Fig. 1, “test 1” and “test 2”). Moreover, with subchronic administration, 30 minutes prior to the administration of an opiate receptor agonist (morphine), the low molecular weight BDNF loop 4 mimetic prevented the formation of secondary reinforcing properties of morphine, statistically significantly reducing the residence time in the right compartment of the chamber associated with the action of morphine (p < 0.05) (Fig. 1, “test”). Moreover, the anti-addictive effect of GSB-106 at a dose of 0.1 mg / kg, which has an antidepressant effect in in vivo experiments, persisted for the next 7 days (“test 2”).

Example 2. The effect of bis- (N-monosuccinyl-L-seryl-L-lysine) hexamethylenediamide upon single and subchronic administration on the manifestation of behavioral signs of morphine withdrawal syndrome in rats

The experiments were performed on outbred male rats (n = 38) with a body weight of 220-250 g.

The results obtained in this example show that bis- (N-monosuccinyl-L-seryl-L-lysine) hexamethylenediamide, or GSB-106, with a single (1 injection) and subchronic (5 injection) administration had a significant effect on specific behavioral parameters withdrawal syndrome (SD) in rats treated with morphine. Compared with the morphine active control group, the total morphine CO index for the M + GSB-106 (1) group decreased by 55.2% (p <0.01), while the effect of GSB-106 with subchronic administration was somewhat weaker, for the group “M + GSB-106 (5)” a decrease in the total CO index by 45.6% (p <0.01) was recorded (Fig. 2).

Assessing the correction of individual manifestations of morphine CO, a decrease or complete elimination of indicators such as piloerection (p <0.01), stereotypy (p <0.01), teeth grinding (p <0.05), rhinorrhea (p <0, 05), shaking off (p <0.05) and attempts to escape (p <0.05) with a single administration of GSB-106 (table 1), which indicates the predominant effect of the low molecular weight BDNF mimetic on the manifestation of signs of canceling an already formed opiate dependence . A less pronounced, but also statistically significant weakening of certain signs of withdrawal was recorded with subchronic administration of GSB-106 for 5 days along with morphine, which primarily affected the reduction of pilo erection (p <0.01), grinding of teeth (p <0.05 ), shaking off (p <0.05) and attempts to escape (p <0.05) (table 1).

The results indicate a positive effect of GSB-106 in stopping the behavioral signs of morphine withdrawal syndrome in rats with a formed opioid dependence in acute and subchronic administration.

In general, the presented experimental data of in vivo experiments indicate the presence of anti-addictive potential in GSB-106, which manifests itself in the prevention of the formation of secondary supporting (motivational) effects of the opioid, and a significant weakening of somatic manifestations with a sharp withdrawal of the opioid.

Thus, the previously obtained data on the antidepressant component in the pharmacological profile of bis- (N-monosuccinyl-L-seryl-L-lysine) hexamethylene diamide and the proven absence of its own narcogenic potential allow us to conclude that it is highly effective as a treatment for opioid dependence.

Description of drawings

FIG. 1. Assessment of the effect of GSB-106 on the secondary reinforcing effects of the opioid analgesic morphine

The experimental groups are presented on the abscissa axis during preliminary testing ("pretest"), after 5 injections of morphine and GSB-106 ("test 1") and 6 days after "test 1"("test2"), on the ordinate axis - time difference, Δ _sec , (s). Experimental groups: 1st column — control group (water for injection, ip); 2nd column - GSB-106 at a dose of 0.1 mg / kg, ip; 3rd column - morphine at a dose of 5 mg / kg, ip; 4th column — morphine at a dose of 5 mg / kg + GSB-106 at a dose of 0.1 mg / kg, ip.

Statistically significant differences compared with the control group (*** - p <0.001), according to the non-parametric Mann-Whitney criterion; in comparison with the results of the pre-test for the morphine group (## - p <0.01, ### - p <0.001), according to the Wilcoxon test for dependent groups; in comparison with the "morphine" group (x - p <0.05), according to the nonparametric Mann-Whitney criterion. Data are presented as mean values.

FIG. 2. Assessment of the influence of GSB-106 on the total index of naloxone-induced withdrawal syndrome in rats

The experimental groups are presented on the abscissa axis, and the total index of withdrawal syndrome in% is shown on the ordinate axis. Experimental groups: 1st column - control group (water for injection), 2nd column - morphine, 3rd column - morphine + GSB-106 at a dose of 0.1 mg / kg with a single dose, 4th column - morphine + GSB-106 at a dose of 0.1 mg / kg with subchronic administration.

** - p <0.01, *** - p <0.001 compared to the control group, ## - p <0.01, ### - p <0.001 compared to the morphine group, according to one-way analysis of variance (ANOVA) and Mann-Whitney U-test, the number of animals in groups of 8-10; data are presented as mean values.

Claims (1)

The use of bis- (N-monosuccinyl-L-seryl-L-lysine) hexamethylene diamide as an agent for the treatment of opioid dependence.

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